The tetrad effect and geochemistry of apatite from the Altay Koktokay No.3 pegmatite,Xinjiang,China:implications for pegmatite petrogenesis
作者单位：Key Laboratory of Mineral ResourcesInstitute of Geology and GeophysicsChinese Academy of Sciences Graduate University of Chinese Academy of Sciences CSIRO Earth Science and Resource Engineering26 Dick Perry Ave.KensingtonWA 6151Australia John de Laeter Center for Isotope ResearchDepartment of Applied GeologyCurtin UniversityPerthWA 6945Australia Department of Earth & Oceanic SciencesThe University of WaikatoPrivate Bag 3105HamiltonNew Zealand
会议名称：《中国科学院地质与地球物理研究所2013年度（第13届）学术年会》
会议日期：2014年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：supported by Key project of the National Science and Technology Support Program(Grant number 2011BAB06BO3-04) Knowledge Innovation Project of Chinese Academy of Sciences (Grant number KZCX2-YW-Q04-08) Ministry of Land and Resources Comprehensive Research for Typical Mineral Deposits (Grant number 20089932)
摘 要：In order to better constrain the evolution and petrogenesis of pegmatite,geochemical analysis was conducted on a suite of apatite crystals from the Altay Koktokay No.3 pegmatite,Xinjiang,China and from the granitic and amphibolitic wall *** samples derived from pegmatite zones show convex tetrad effects in their REE patterns, extremely negative Eu anomalies and non-chondritic Y/Ho *** contrast,chondritic Y/Ho ratios and convex tetrad effects are observed in the muscovite granite suggesting that different processes caused non-chondritic Y/Ho ratios and lanthanide tetrad *** on the occurrence of convex tetrad effects in the host rocks and their associated *** propose that the tetrad effects are likely pro- duced from immiscible fluoride and silicate *** is in contrast to previous explanations of the tetrad effect;i.e. surface weathering,fractional crystallization and/or fluid- rock ***,we put forward that extreme negative Eu and non-chondritic Y/Ho in apatite are likely caused by the large amount of hydrothermal fluid exsolved from the pegmatite *** of melt composition was found to be the primary cause of inter and intra-crystal major and trace element variations in *** entering into apatite via substitution of Ca is supported by the pos- itive correlation between CaO and *** evolution trends in apatite composition imply different crystallization environments between wall rocks and pegmatite zones. Based on the geochemistry of apatite samples,it is likely that there is a genetic relationship between the source of muscovite granite and the source of the pegmatite.